(a) Field of the Invention
The present invention relates to a stud bolt. More particularly, the present invention relates to a rivet stud bolt (RSB) for mechanically assembling an element to a base such as a panel, and a panel joint structure with the rivet stud bolt.
(b) Description of the Related Art
In automotive industries, a weld bolt, a weld nut, a stud bolt, and so on are applied to mount an element such as an engine, a transmission, a steering system, and so on to a base such as a vehicle panel, a frame, and so on.
Generally, a stud bolt including a bolt portion and a flange is connected to the base by welding the flange to the base.
For example, the flange of the stud bolt is instantaneously melted by arc discharge then the flange is welded to the base.
However, in arc welding, soot is generated near the welding portion of the base and the flange portion, positions of the stud bolt are various, deformation of the welded portion may be generated, and the stud bolt may be easily disassembly due to weak connecting strength.
For overcoming the drawbacks described above, a stud bolt including a bolt portion, a flange and a rivet portion integrally formed for mechanical connection has been developed, for example, U.S. Pat. No. 7,287,944.
In mechanical connection using the stud bolt, an assembling hole is formed to a base, the rivet portion is inserted into the assembling hole, and then the rivet portion is plastically deformed by pressing the stud bolt to connect the stud bolt to the base.
In this case, the rivet portion shaped as a hollow cylinder is plastically deformed to fit the base.
For example, the rivet portion of the rivet stud bolt penetrates the hole of the base by a punch of a setting tool, is outwardly deformed by a forming groove of a die (also called an anvil), and then is press-fitted to the base.
However, the plastically deformed portion is deformed as a ring so that the connection strength of the rivet portion is not sufficient.
Therefore, the stud bolt may be rotated.
Also, since the end of the rivet portion is deformed as an annular edge, the setting tool requires a heavy load for plastically deforming the rivet portion.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.